exposed group

in epidemiology
synonym: exposed
https://doi.org/10.1351/goldbook.15696
People (or other organisms) who have been exposed to a supposed cause of a disease or health state of interest, or possess a characteristic that is a determinant of the health outcome of interest.
Source:
PAC, 2007, 79, 1153. (Glossary of terms used in toxicology, 2nd edition (IUPAC Recommendations 2007)) on page 1220 [Terms] [Paper]